In general, polyolefins are characterized by excellent properties in moldability, thermal resistance, mechanical characteristics, hygienic adaptability, and steam permeation resistance, and with excellent appearance as molded articles. Therefore, they are widely used in extrusion molded articles, blow molded articles, injection molded articles, etc.
However, since the polyolefins are so-called non-polar resins without polar groups in the molecule, they are poor in the affinity with various polar materials including metals, and have difficulties in laminating and using these materials.
Thus, improvement of the affinity with polar materials by graft polymerization of maleic anhydride to the polylolefins has widely been used, but the improvement for some adherends is sometimes inadequate, hence a modified polyolefin having higher adhesive force to polar materials is desired.
On the other hand, liquid crystal (hereafter referred to as LC) polymers including all the aromatic polyesters have excellent chemical resistance and gas barrier properties, and application to packaging materials for vessels, gasoline tanks of automobiles, etc. has been expected. However, the LC polymer in general has properties of high tendency for orientation in the direction of flow at melting, and hence has high strength in the molding direction but low strength in the direction perpendicular to molding. Also, because the LC polymers are expensive, it is necessary to use them by laminating with polymers such as the polyolefins.
Adhesiveness between the LC polymers and the polyolefins in conventional thermal fusion is poor, and certain adhesive resins are necessary to laminate them.
Various investigations have so far been performed on the adhesive resins for the LC polymers and the polyolefins. These adhesive resins are mainly copolymers manufactured by radical copolymerization of ethylene and a polar monomer such as (meth)acrylic acid under high pressure. Since many long-chain branches are formed in a polymerization reaction, copolymers with high crystallinity are difficult to be manufactured; hence there were cases in which the adhesive strength is extremely decreased when the copolymers were applied to usage in direct contact with a solvent such as gasoline or to usage for fatty food materials.